Jeff Tweedy isn’t really the nostalgic type, but he has spent the past few years working on his memoir, “Let’s Go (So We Can Get Back),” candidly revisiting his rise from the suburbs of Illinois to frontman for the Grammy-winning rock band Wilco. At 51, he has survived ego battles, record industry upheaval and an addiction to painkillers brought on by severe migraines. Now he can let go. Unlike the circuitous, dense songs that made up the group’s most celebrated releases, like 2004’s “A Ghost Is Born” and 2007’s “Sky Blue Sky,” the music on Tweedy’s latest solo album, “Warm,” is intimate and uncomplicated, in keeping with the fast and loose style he has nurtured in the past decade. On “Having Been Is No Way to Be,” he simply blurts, “Now people say, what drugs did you take/ And why don’t you start taking them again?/ But they’re not my friends/ And if I was dead what difference would it ever make to them?” But Tweedy is selling himself short. By reconnecting with his roots, the songwriter has also rediscovered that laser-sharp focus that propelled the band through three decades of adventurous music. And while they may be free of frills, songs like “I Know What It’s Like,” with its gentle country lilt, and “Let’s Go Rain,” which feels like a mild-mannered rave-up, just might represent Tweedy’s best work in years. — Aidin Vaziri